Mobile station position estimation using transmitter almanac information

ABSTRACT

A method for estimating positions of a mobile station includes: sending a request, from the mobile station, for almanac information for wireless transmitters of one or more wireless communications networks, the request including one or more indications of one or more routes; receiving, at the mobile station, the almanac information for wireless transmitters of the one or more wireless communications networks, the almanac information being for a subset of wireless transmitters of the wireless transmitters of the one or more wireless communications networks, the subset of wireless transmitters being expected to contribute to position estimations of the mobile station along the one or more routes; acquiring signals, at the mobile station, from wireless transmitters of the subset of wireless transmitters; and estimating, at the mobile station, positions of the mobile station using at least one of the acquired signals.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/105,132, filed Dec. 12, 2013, entitled “Providing wirelesstransmitter almanac information to mobile station based on expectedcontribution to future navigation operation,” which is a continuation ofU.S. application Ser. No. 13/046,542, granted as U.S. Pat. No.8,634,850, filed Mar. 11, 2011, entitled “Providing wireless transmitteralmanac information to mobile station based on expected contribution tofuture navigation operation,” both of which are incorporated herein byreference and assigned to the assignee hereof.

BACKGROUND

I. Field of the Invention

The subject matter disclosed herein relates to determining wirelesstransmitter almanac information to transmit to a mobile station, andmore particularly to basing such determinations on expectedcontributions of one or more wireless transmitters to a futurenavigation operation for the mobile station.

II. Background

The position of a mobile station, such as a cellular telephone, may beestimated based on information gathered from various systems. One suchsystem may comprise a Global Navigation Satellite System (GNSS), whichis one example of a satellite positioning system (SPS). SPS systems suchas GNSS may comprise a number of space vehicles (SV) orbiting the earth.Another example of a system that may provide a basis for estimating theposition of a mobile station is a cellular communication systemcomprising a number of terrestrial wireless transmitters/receivers,often referred to as “base stations,” to support communications for anumber of mobile stations. A further example of a system that mayprovide a basis for estimating the position of a mobile station is awireless network compatible with one or more of the Institute ofElectrical and Electronics Engineers (IEEE) 802.11 wireless local accessnetwork (WLAN) standards, which may also be referred to as a Wi-Finetwork. Such a network may include wireless transmitters/receiversoften referred to as “access points,” for example.

A position estimate, which may also be referred to as a position “fix”,for a mobile station may be obtained based at least in part on distancesor ranges measured from the mobile station to one or more wirelesstransmitters, and also based at least in part on knowledge of thelocations of the wireless transmitters. Such transmitters may compriseSVs in the case of an SPS, terrestrial base stations in the case of acellular communications system, or Wi-Fi/802.11x access or points orother beacon transmitters, for example.

BRIEF SUMMARY

In an aspect, a likelihood of having one or more signals acquired by amobile station may be determined for individual wireless transmitters ofa plurality of wireless transmitters. A subset of wireless transmittersmay be determined based, at least in part, on the determined likelihoodsfor the individual wireless transmitters, and in a further aspect, oneor more signals indicative of almanac information for the subset ofwireless transmitters may be transmitted to the mobile stations.

In an aspect, a method for developing almanac information, the methodcomprising: determining a subset of wireless transmitters from aplurality of wireless transmitters, based, at least in part, on aproximity to a route of a mobile station and an expected contributionfor each of the plurality of wireless transmitters; and identifying thealmanac information for the subset of wireless transmitters.

In a further aspect, a computing platform for developing almanacinformation, the computing platform comprising: a transceiver; and aprocessor, coupled to the transceiver, wherein the processor: determinesa subset of wireless transmitters from a plurality of wirelesstransmitters, based, at least in part, on a proximity to a route of amobile station and an expected contribution for each of the plurality ofwireless transmitters; and identifies the almanac information for thesubset of wireless transmitters.

In an additional aspect, an apparatus for developing almanacinformation, the apparatus comprising: means for determining a subset ofwireless transmitters from a plurality of wireless transmitters, based,at least in part, on a proximity to a route of a mobile station and anexpected contribution for each of the plurality of wirelesstransmitters; and means for identifying the almanac information for thesubset of wireless transmitters.

Additionally, in an aspect, a non-transitory computer-readable mediumincluding program code stored thereon, comprising: program code todetermine a subset of wireless transmitters from a plurality of wirelesstransmitters, based, at least in part, on a proximity to a route of amobile station and an expected contribution for each of the plurality ofwireless transmitters; and program code to identify almanac informationfor the subset of wireless transmitters.

In a further aspect, an expected contribution to a future navigationoperation of a mobile station may be determined at the mobile stationfor individual wireless transmitters of a plurality of wirelesstransmitters, based, at least in part, on a value of the expectedcontribution and a likelihood of having one or more signals acquired bythe mobile station for the individual wireless transmitters of theplurality of wireless transmitters. Information indicative of theexpected contribution of the mobile station may be transmitted from themobile station to an almanac server, and one or more signals indicativeof almanac information may be received at the mobile station from thealmanac server, the almanac information associated with a subset ofwireless transmitters determined from the plurality of wirelesstransmitters based at least in part on the expected contribution for theindividual wireless transmitters.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive examples will be described withreference to the following figures, wherein like reference numeralsrefer to like parts throughout the various figures.

FIG. 1 is a schematic block diagram of an example global navigationsatellite system (GNSS) and an example cellular network.

FIG. 2 is a schematic block diagram illustrating an example mobilestation.

FIG. 3 is an illustration depicting an example almanac server incommunication with a number of mobile stations via one or more wirelesscommunications networks.

FIG. 4 is an illustration of an example process for delivering almanacinformation to a mobile station.

FIG. 5 is a schematic diagram illustrating an example hierarchalorganization for a wireless transmitter almanac.

FIG. 6 is an illustration of a map depicting example locations for anumber of wireless transmitters.

FIG. 7 is a flow diagram of an example process for determining a subsetof wireless transmitter almanac information, based at least in part onan expected contribution to a future navigation operation of a mobilestation.

FIG. 8 is a schematic block diagram depicting an example mobile station.

FIG. 9 is a schematic block diagram of an example computing platform.

DETAILED DESCRIPTION

As discussed above, information in an almanac may be used to perform, atleast in part, position estimation operations for mobile stations. Aposition estimate for a mobile station may be obtained based at least inpart on distances or ranges measured from the mobile station to one ormore transmitters such as space vehicles (SV), terrestrial basestations, or access points, for example, and also based at least in parton the locations of the one or more transmitters. The range to thetransmitters may be measured based on one or more characteristics of oneor more signals transmitted by the transmitters and received at themobile station. The location of the transmitters may be ascertained, inat least some cases, based on the identities of the transmitters, andthe identities of the transmitters may be ascertained from signalsreceived from the transmitters.

An almanac may be maintained for systems used for position estimation.The almanac may contain various types of information, including, forexample, information that may be used in position estimation operations.Such information may include the identities and locations of variouswireless transmitters of one or more wireless communications systems,for example.

For some wireless communications systems, an almanac that storesinformation related to land-based transmitters may be referred to as a“base station almanac” (BSA). The terms “almanac” and “base stationalmanac” as used herein may be used interchangeably, and are meant toinclude any organized set of information related to a plurality oftransmitters of a wireless communications network. A BSA may be storedin a memory of a computing platform, such as a BSA server, for example,or in a memory of mobile station, for another example. In anotheraspect, a BSA may be transmitted from a BSA server to one or more mobilestations.

In one aspect, a mobile station may use received almanac information toperform position estimation operations, for example by trilateration ormultilateration, using information and measurements from a number oftransmitters. A mobile station may also use received almanacinformation, in another aspect, to narrow a code phase search window foracquiring signals transmitted by an SPS in order to perform positionestimation operations using, at least in part, measurements from signalsreceived from one or more space vehicles (SV). For example, to narrow asearch window, a mobile station may use BSA information to associate anidentification of a cellular communication system sector currentlyserving the mobile station with an almanac entry. The entry may providea location of the transmitter for the serving sector, from which anapproximate location (within a couple of kilometers, for example) of themobile station may be obtained.

Mobile stations may have a limited capacity for storing information, dueat least in part to size and cost considerations. Also, wirelesscommunication channels may have limited bandwidth. Therefore, it may beadvantageous to provide a mobile station with almanac information it ismore likely to utilize in position fix operations and to not provide themobile station with information it is unlikely to utilize. In thismanner, the amount of almanac information to be stored at the mobilestation may be kept within limits imposed by storage capacity, and theamount of communication channel bandwidth utilized in transmittingalmanac information may be reduced.

In an aspect, a subset of a plurality of wireless transmitters may bedetermined based, at least in part, on expected contributions to afuture navigation operation of a mobile station. Expected contributionsmay be determined, at least in part, based on a value of an expectedcontribution and a likelihood of having one or more signals acquired bythe mobile station for the individual wireless transmitters. Determiningthe subset of wireless transmitters may comprise determining whether thelikelihoods for the individual wireless transmitters exceed apre-selected threshold. In a further aspect, one or more signalsindicative of almanac information for the subset of wirelesstransmitters may be transmitted to the mobile station. An amount ofalmanac information delivered to a mobile station may further be limitedby a specified maximum amount, in an aspect, although the scope ofclaimed subject matter is not limited in this respect. In this manner,the mobile station has stored thereon almanac information it is mostlikely to utilize in performing position fix operations, and the amountof extraneous information delivered to the mobile station and storedthereon may be minimized, at least to an extent. Also, the amount ofcommunication channel bandwidth utilized to deliver the almanacinformation to the mobile station may be minimized, again at least to anextent.

FIG. 1 is a schematic block diagram of an SPS 110 and a wirelesscommunications network 120 in communication with a mobile station 150.Wireless communications network 120, for this example, may comprise acellular communications network capable of enabling voice communicationfor a number of mobile stations including mobile station 150, forexample, and may further support position estimation for the mobilestations in addition to providing voice communication. Wirelesscommunications network 120 may comprise any of a number of networktypes, several examples of which are described below. Wirelesscommunications network 120 for this example comprises base stations 132,134, and 136 that provide communication for a number of wirelessterminals such as, for example, mobile station 150. For simplicity, onlya few base stations 132, 134, and 136 are depicted and one mobilestation 150 is depicted in FIG. 1. Of course, other examples may includeadditional numbers of base stations, and the configuration of basestations depicted in FIG. 1 is merely an example configuration. Also,wireless communications network 120 is merely an example wirelesscommunications system, and the scope of claimed subject matter is notlimited in this respect.

As used herein, the term “wireless transmitter” is meant to include anywireless communication station or device used to facilitatecommunication in a wireless communications system, such as, for example,a cellular network, although the scope of claimed subject matter is notlimited in this respect. An example type of wireless transmitterutilized in a cellular network may be referred to as a base station. Inanother aspect, a wireless transmitter may comprise a femtocell,utilized to extend cellular telephone service into a business or home.In such an implementation, one or more mobile stations may communicatewith a femtocell via a code division multiple access (CDMA) cellularcommunication protocol, for example, and the femtocell may provide themobile station access to a larger cellular telecommunication network byway of another broadband network such as the Internet. In anotheraspect, wireless transmitters may be included in any of a range ofelectronic device types. In an aspect, a wireless transmitter maycomprise a wireless local area network (WLAN) access point, for example.Such a WLAN may comprise a network that is compatible with one or moreof the IEEE 802.11x standards, in an aspect, although the scope ofclaimed subject matter is not limited in this respect. Additionally, theuse of the term “transmitter” in describing a device does not limit thatdevice's function to transmitting only. For example, base stations andaccess points are typically capable of both transmitting and receivingwireless signals.

As used herein, the term “mobile station” (MS) refers to a device thatmay from time to time have a position that changes. Such changes inposition may comprise changes to direction, distance, orientation, etc.,as a few examples. In particular examples, a mobile station may comprisea cellular telephone, wireless communication device, user equipment,laptop computer, other personal communication system (PCS) device,personal digital assistant (PDA), personal audio device (PAD), portablenavigational device, or other portable communication devices. A mobilestation may also comprise a processor or computing platform adapted toperform functions controlled by machine-readable instructions.

In an aspect, SPS 110 may comprise a number of SVs, for example SVs 112,114, and 116. For an example, SPS 110 may comprise one or more satellitepositioning systems, such as GPS, GLONASS and Galileo, although thescope of claimed subject matter is not limited in this respect. In oneor more aspects, mobile station 150 may receive signals from SVs 112,114, and 116, and may communicate with one or more of base stations 132,134, and 136. For example, mobile station 150 may obtain one or moremeasurements from one or more signals received from one or more of theSVs or base stations. However, in some circumstances timing signals froman SPS may not be available. In such a circumstance, mobile station 150may gather propagation delay information through communication with oneor more of base stations 132, 134, or 136. Mobile station 150 maycalculate a position for the mobile station based, at least in part, ontiming calibration parameters received through communication with one ormore of base stations 132, 134, or 136, and further based, at least inpart, on known locations of the base stations. Mobile station 150 mayalso make use of an estimated propagation delay for signals receivedfrom a base station source, a satellite source, or both, to measureranges to such sources.

In another aspect, position determination calculations may be performedby a network entity such as, for example, location server 170 depictedin FIG. 1, rather than at mobile station 150. Such a calculation may bebased, at least in part, on information gathered by mobile station 150from one or more of base stations 132, 134, or 136. In a further aspect,location server 170 may transmit the calculated position to mobilestation 150.

A mobile switching center (MSC) 140 for this example may be coupled tobase stations 132, 134, and 136, and may further couple to other systemsand networks, such as a public switched telephone network (PSTN), apacket data serving node (PDSN) 160, and so on. MSC 140 for this exampleprovides coordination and control for the base stations coupled to itand further controls the routing of data to/from the mobile stationsserved by these base stations. For the example depicted in FIG. 1, PDSN160 may couple MSC 140 to location server 170 and to a BSA server 180.Location server 170 may collect and format location data, provideassistance to mobile stations for position estimation, or performcomputations to obtain position estimates for the mobile stations. BSAserver 180 manages a BSA 185, which for this example stores a hierarchalbase station almanac for wireless communications network 120. An exampleof a hierarchal base station almanac is presented below in connectionwith FIG. 5.

In one aspect, BSA server 180 may provide almanac information to mobilestation 150. Information to be provided to mobile station 150 maycomprise a subset of BSA 185 selected based, at least in part, uponexpected contributions to future navigation operations for mobilestation 150. In an aspect, expected contributions may be determined, atleast in part, based on likelihoods of having one or more signalsacquired by a mobile station for individual wireless transmitters orbased on a value of the expected contribution. The term “acquire” asused herein as it relates to wireless signals received at a mobilestation refers to a mobile station obtaining sufficient information froma wireless signal to enable processing of the received wireless signalto obtain at least some data transmitted therein. Example types ofinformation that may be obtained by a mobile station in acquiring awireless signal may include, but are not limited to, carrier frequency,radio-frequency (RF) phase, code, code-phase, timing, or Doppler shift,to list but a few examples. Further, it should be noted that the scopeof claimed subject matter is not limited to any particular technique foracquiring a wireless signal.

In determining expected contributions to future mobile stationnavigation operations, any of a range of types of information may beconsidered. For example, in an aspect, an expected contribution to afuture mobile station may be determined based, at least in part, on oneor more of a ranging capability, an expected measurement accuracy, anexpected observation accuracy, a coverage area size, or informationrelated to an importance in past navigation operations for theindividual wireless transmitters. However, these are merely exampletypes of information that may be used in determining an expectedcontribution, and the scope of claimed subject matter is not limited inthis respect. In an additional aspect, any of a range of types ofinformation may be considered in determining likelihoods of having oneor more signals acquired by a mobile station for individual wirelesstransmitters. For example, in an aspect, such likelihoods may be based,at least in part, on an individual transmitter's proximity to a currentlocation of a mobile station. In another aspect, such likelihoods may bebased, at least in part, on how often a mobile station acquired signalsfrom an individual wireless transmitter in the past. In a furtheraspect, such likelihoods may be based, at least in part, on anindividual transmitter's proximity to a historical route of a mobilestation. Other examples of information upon which such likelihoods maybe based may include radio access types supported by a mobile station,carrier frequencies for individual radio access types supported by amobile station, radio access types currently enabled on a mobilestation, and how often an individual wireless transmitter has signalsacquired by a plurality of other mobile stations reporting theirobservations to a network server such as location server 170. Of course,these are merely examples of types of information that may be utilizedin determining likelihoods of having one or more signals acquired by amobile station for individual wireless transmitters of a plurality ofwireless transmitters, and the scope of claimed subject matter is notlimited in this respect.

In another aspect, information to be provided to mobile station 150 maycomprise a subset of BSA 185 selected based, at least in part, upon oneor more additional parameters specified by the mobile station. Suchparameters may include, for example, one or more networks orsub-networks specified by mobile station 150, the amount of that thedata mobile station 150 tells the network it can store, the specificcontent of the data, or the granularity of the data, to name but a fewexamples of parameters that may be specified by the mobile station.

FIG. 2 is a schematic block diagram of an example implementation ofmobile station 322. In an aspect, mobile station 322 comprises an SPSreceiver 210 and a wireless communication transceiver 220. Thus, mobilestation 322 may communicate both with one or more SPS such as SPS 110and one or more terrestrial wireless networks, such as wirelesscommunications network 120, which may comprise a cellular network in anaspect, or may comprise a WLAN, in another aspect. In another aspect,mobile station 322 may further comprise a memory device that ispartitioned, in one example, to store position fix information in a fixdatabase 230 and to store base station almanac information in a basestation almanac (BSA) 240.

Fix information stored in fix database 230 may comprise informationgathered in the course of position fix operations. Such position fixinformation may be stored in transmitter database 250 of mobile station322 in what may be referred to as a “fix database” in which the fixinformation is organized or indexed according to particular instances ofposition fixes. Fix information may also be stored in a transmitterdatabase 250 in which fix information may be organized or indexedaccording to particular wireless transmitters observed or identifiedduring position fix operations. In a further aspect, mobile station 322may comprise one or more sensors that for this example are incorporatedinto Inertial Measurement Unit (IMU) 270 that may be utilized indead-reckoning navigation operations, for example. Mobile station 322further comprises processor 260, for this example. Of course, this ismerely one example of a configuration of a mobile station, and the scopeof claimed subject matter is not limited in this respect.

In an aspect, location information for a plurality of wirelesstransmitters may be stored in a network entity such as BSA server 180 inwireless communications network 120, or may be stored in any of a widerange of other resources in the wireless network. Further, for anexample, location information for wireless transmitters may compriselongitude and latitude, and may for another example also comprisealtitude information. However, these are merely examples of locationinformation for wireless transmitters, and the scope of claimed subjectmatter is not limited in this respect. In another aspect, some wirelesstransmitters may broadcast their locations, and such locationinformation may be stored in one or more databases in the mobilestation, such as in transmitter database 250 of mobile station 322. Suchwireless transmitter location information may be shared with othernetwork entities, such as an assistance server or location server suchas location server 170 of FIG. 1, for example.

Further, in an additional aspect, BSA 240 may have stored therein asubset of a larger BSA database, such as BSA 185 of FIG. 1, for example.In an aspect, a network entity such as location server 170 or BSA server180 may determine which of a plurality of wireless transmittersassociated with information stored in BSA 185 are likely to have one ormore signals acquired by mobile station 322 and may further determineexpected contributions to a future mobile station 322 navigationoperation for individual wireless transmitters of the plurality ofwireless transmitters. As mentioned previously, an expected contributionto a future mobile station may be determined based, at least in part, onone or more of a ranging capability, an expected measurement accuracy,an expected observation accuracy, a coverage area size, or informationrelated to an importance in past navigation operations for theindividual wireless transmitters. Further, likelihoods of having one ormore signals acquired by mobile station 322 for individual wirelesstransmitters may be based, at least in part, on an individualtransmitter's proximity to a current location of mobile station 322. Inanother aspect, the likelihoods may be based, at least in part, on anumber of occurrences over a period of time in which mobile station 322has acquired signals from an individual wireless transmitter in thepast. In a further aspect, the likelihoods may be based, at least inpart, on an individual transmitter's proximity to a historical route ofmobile station 322. Other examples of information upon which thelikelihoods may be based may include radio access types supported bymobile station 322, rates of use for the individual radio access typessupported by mobile station 322, radio access types currently enabled onmobile station 322, and how often an individual wireless transmitter hassignals acquired by a plurality of other mobile stations reporting theirobservations to a network server such as location server 170. Of course,these are merely examples of information that may be utilized indetermining likelihoods of having one or more signals acquired by amobile station for individual wireless transmitters of a plurality ofwireless transmitters, and the scope of claimed subject matter is notlimited in this respect.

In an aspect, in order for a network entity such as location server 170or BSA server 180 to determine expected contributions and likelihoods ofhaving one or more signals of a particular wireless transmitter acquiredby mobile station 322, the network entity may receive information frommobile station 322. As mentioned above, mobile station 322 may collectinformation related to position fix operations in fix database 230,including information identifying and locating transmitters observedduring the position fix operations. Information related to specifictransmitters may be stored, for one example implementation, intransmitter database 250. Information stored in fix database 230 ortransmitter database 250 may be provided to the network entity, such asto location server 170 or to BSA server 180, in an exampleimplementation. Information provided to wireless communications network120 may provide wireless communications network 120 with sufficientinformation to determine likelihoods of having one or more signals of atleast some wireless transmitters acquired by mobile station 322. Ofcourse, just as information may be determined regarding transmittersfrom which a mobile station has acquired signals in the past,information may also be determined regarding transmitters from which amobile station has not acquired signals in the past. Transmitters fromwhich a mobile station has not acquired signals in the past may bedetermined to have a relatively small likelihood of having one or moresignals acquired by mobile station 322, in an aspect.

FIG. 3 is an illustration depicting an example base station almanac(BSA) server 350 in communication with a number of mobile stations 320via one or more wireless communications networks 330, such as, forexample, WLAN 332 and cellular network 334, and via Internet 340. Forthis example, mobile station 322 may represent a multimode device thatmay support communication with both packet-switched wireless local areanetwork (WLAN) 332 and cellular network 334. Of course, these are merelyexamples of the types of wireless communications networks with which amultimode device may communicate, and the scope of claimed subjectmatter is not limited in this respect. Also for this example, mobilestation 324 may represent a single mode device that may supportcommunication with cellular network 334. Again, the cellular network ismerely one example of a wireless communications network with which amobile station may establish communication.

FIG. 3 further depicts a number of transmitter types 310 that mobilestations 320 may monitor. Mobile stations 320 may or may not besubscribed to any given network associated with the various respectivetransmitter types to be able to monitor signals transmitted from thevarious transmitter types. Therefore, BSA information provided to themobile stations may or may not include information associated withnetworks to which the mobile stations are not subscribed. Mobilestations may specify particular networks or particular transmitter typesif making requests for BSA information. For the example of FIG. 3, oneor more of mobile stations 320 may request BSA information comprising atleast a subset of a BSA from BSA server 350.

In another aspect, BSA server 350 may obtain a BSA from an externalalmanac source 360. For example, a cellular network provider maycontract with a third party to develop or provide BSA information to BSAserver 350. At least a subset of this information may eventually betransmitted to one or more of mobile stations 320. In a further aspect,BSA server 350 may receive BSA information from one or more of mobilestations 320 as one or more of mobile stations 320 develop suchinformation at least in part through monitoring signals transmitted fromone or more of example transmitters 310. Additionally, in anotheraspect, one or more of mobile stations 320 may select whetherexternally-provided BSA information should be delivered to the mobilestation in response to the mobile station making such request or whetherBSA information originally developed at least in part by the mobilestations should be delivered. In a further aspect, one or more of mobilestations 320 may select a combination of information from external andlocal sources.

Although the example of FIG. 3 depicts two mobile stations, in practicea wide variety of mobile station types exhibiting a wide range ofdifferent functionalities or storage capabilities may be utilized tocommunicate with a large variety of potential network types. Further,the mobile stations may exhibit a wide range of different usagepatterns. Therefore, it may be advantageous for BSA server 350 toprovide individualized subsets of BSA information that the individualmobile stations may require or request, and it may be furtheradvantageous to provide such information formatted in a flexible manneraccording to a specified file size, coverage area, or transmitter type,to name but a few examples of parameters that may be specified. In oneaspect, these parameters may be specified by the mobile stations.

In an additional aspect, transmitters whose information is to beincluded in the BSA information provided to a requesting mobile stationmay be determined according to the proximity of individual transmittersto a current estimated location of the requesting mobile station. Theidea behind this technique for determining which BSA information toprovide to a requesting mobile station is that the requesting mobilestation may be more likely to acquire signals in the relatively nearfuture for those wireless transmitters whose coverage areas intersect aspecified geometric shape surrounding the estimated location of themobile station. In an aspect, the shape may comprise a circle with aspecified radius extending from the estimated location of the requestingmobile station. For one example, if an individual coverage area for atransmitter intersects the shape, or is wholly enclosed by the shape, orsomewhere in between (for example, the estimated center of the coveragearea is inside the shape), the given transmitter may have itsinformation included in the BSA information provided to the requestingmobile station. For yet another example, the determination of whether toinclude information for a given group of transmitters in the BSAinformation to be provided to a requesting mobile station may be madeconditionally, based at least in part on data storage available in therequesting mobile station. For example, information for eitherindividual transmitters or for groups of transmitters may be included,depending upon space availability, where information is added until aBSA information size threshold is reached. The BSA information size maybe based, for example, upon a maximum size or upon a desired size ofavailable data storage in the requesting mobile device.

FIG. 4 is an illustration of an example process 400 for deliveringalmanac information to a mobile station. More particularly, FIG. 4illustrates an example process for delivering a subset of a networkalmanac 410 to mobile station 322. In an aspect, network almanac 410 maycomprise information related to a plurality of wireless transmitters.Network almanac 410 may comprise information, in an exampleimplementation, for a plurality of cellular base stations and also for aplurality of WLAN access points. However, the scope of claimed subjectmatter is not limited to any particular type of transmitter. Networkalmanac 410 may store any of a wide range of information types for theplurality of base stations and the plurality of access points,including, for example, location information for at least some of thetransmitters. Other types of information that may be stored in networkalmanac 410 or provided to mobile station 322 are described in moredetail below in connection with FIG. 5.

For the example process 400, a partitioning manager 420 may partitionnetwork almanac 410 into a number of regional almanac partitions 430 anda number of sparse network almanac (SNA) 440 partitions. A “sparsenetwork almanac” may relate to an almanac comprising groupings of basestations or access points. The groupings may generally be associatedwith hierarchal identity elements for individual networks represented inthe almanac and their underlying regions. Regional almanac partitions430 may comprise more detailed information partitioned, as the nameimplies, according a geographic region.

Download manager 450, in an aspect, may determine which information toprovide to mobile station 322 by way of a mobile download 460. In anaspect, download manager 450 may select information to provide to mobilestation 322 based, at least in part, on expected contributions fromindividual wireless transmitters associated with information stored innetwork almanac 410 to future navigation operations for mobile station322. Expected contributions may be determined, for example, based atleast in part on one or more of a ranging capability, an expectedmeasurement accuracy, an expected observation accuracy, a coverage areasize, or information related to an importance in past navigationoperations for the individual wireless transmitters. Also, informationmay be selected based, at least in part, on which of a plurality ofwireless transmitters associated with information stored in networkalmanac 410 are likely to have one or more signals acquired by mobilestation 322. The likelihoods may be based, at least in part, on anindividual transmitter's proximity to a current location of mobilestation 322, or, in another aspect, the likelihoods may be based, atleast in part, on the a number of occurrences over a period of time inwhich mobile station 322 has acquired signals from an individualwireless transmitter in the past. For additional examples, thelikelihoods may be based, at least in part, on an individualtransmitter's proximity to a historical route of mobile station 322, or,in another aspect, the likelihoods may be based, at least in part, onradio access types supported by mobile station 322. Likelihoods may alsobe based, at least in part, on rates of use for the individual radioaccess types supported by mobile station 322, on radio access typescurrently enabled on mobile station 322, or may also be based, at leastin part, on how often an individual wireless transmitter has signalsacquired by a plurality of other mobile stations reporting theirobservations to a network entity such as download manager 450. Ofcourse, these are merely examples of information that may be utilized indetermining likelihoods of having one or more signals acquired by amobile station for individual wireless transmitters of a plurality ofwireless transmitters, and the scope of claimed subject matter is notlimited in this respect.

Mobile station 322 may provide requests for network almanac informationthrough an upload manager 470, in an aspect, and download request 401may be forwarded to download manager 450. Also, as mentioned previously,mobile station 322 may provide wireless transmitter information storedin fix database 230 or transmitter database 250 to a network entity,which, for the example depicted in FIG. 4, comprises upload manager 470.Upload manager 470 may further collect wireless transmitter informationfrom a number of other mobile stations, and such information may beadded to network almanac 410. In another aspect, as additionalinformation is gathered from various mobile stations for at least someof the wireless transmitters represented in network almanac 410,information may be refined and made more accurate as additional pointsof reference are obtained. For example, a first mobile station mayreport a location for a particular wireless transmitter. A second mobilestation may report a location for that particular wireless transmitterthat is somewhat different from that reported by the first mobilestation. With just the two points of reference, it may be difficult inthis particular example to determine a reasonably accurate location forthe particular wireless terminal. However, if additional reports may beobtained from additional mobile stations or from the same first andsecond mobile stations at later points in time and at differentlocations, a more accurate estimate of the location of the particulartransmitter may be obtained.

FIG. 5 is a schematic diagram illustrating an example hierarchalwireless transmitter almanac 500. For this example, the hierarchalstructure may store information related to a WLAN. However, in thediscussion below, elements related to cellular wireless communicationsare also discussed, as the hierarchal organization that is illustratedmay be used for any type of network. As previously noted, mobilestations may have a limited capacity for storing information, due atleast in part to size and cost considerations. Typically, muchinformation included in a base station almanac is repetitive due tosimilar parameters stored for most or all sectors for most or alltransmitters across a wireless communications system, such as a cellularsystem. The information related to the various transmitters may bestored as a flat listing, where specified information for individualtransmitters is stored in separate entries for all of the individualsectors for all of the individual transmitters, for example. Therefore,because of the repetitive nature of the transmitter information, andbecause of a mobile station's limited capacity for storing suchinformation, it may be advantageous to more efficiently storetransmitter information in a base station almanac by reducingunnecessary duplication of information.

In one aspect, information for a base station almanac may be storedusing a hierarchal organization. The hierarchal organization maycomprise a number of levels. In one example, a topmost level maycomprise a header, and the lowest level may comprise an access pointidentification level 550 in the case of a wireless communications systemsuch as WLAN 332, or for a wireless communications system such ascellular network 334, the lowest level may comprise a sectoridentification (SECTOR_ID) level. Rather than repeating information thatmay be common across all or nearly all access points or sectors, thecommon information may be stored in the header. In this manner, a singleinstance of the common information may be stored in the header, and thatinformation need not be repeated in all of the access point or sectorentries. In one aspect, it is understood that the information stored inthe header is applicable to all entries of the access pointidentification or sector identification level unless any exceptions arenoted in individual entries of the access point identification or sectoridentification levels. In general, any information that would otherwisebe repeated in a substantial number of entries of a conventional basestation almanac may be stored in a single entry in an upper level of ahierarchal base station almanac, thereby greatly reducing the amount ofrepetition that would otherwise be found in conventional base stationalmanacs.

Hierarchal wireless transmitter almanac 500 in one aspect may representa BSA stored at a BSA server such as BSA servers 180 or 350. In anotheraspect, hierarchal wireless transmitter almanac 500 may represent BSAinformation to be transmitted to a mobile station and stored in themobile station. One example type of wireless communications network maycomprise a code division multiple access (CDMA) network. A CDMA networkmay comprise ID parameters that may be organized hierarchically.Therefore, it may be advantageous to convey an almanac for a given setof transmitters in a hierarchal fashion. Similarly, ID parameters forWLAN 332 may be organized in a hierarchal fashion. For the exampledepicted in FIG. 5, hierarchal wireless transmitter almanac 500 maycomprise a plurality of hierarchal levels, such as header level 510, asystem identification (SID) level 520 that may comprise one or moresystem identification level entries, a network identification level(NID) 530 that may comprise one or more network identification levelentries, a region identification level 540 in the case of a WLAN or acell identification level in the case of a cellular network, and accesspoint identification level 550 in the case of a WLAN or a sectoridentification level in the case of a cellular network. For the exampleof FIG. 5, SID level 520 comprises a pair of entries SID 521 and SID522, NID level 530 comprises entries NID 531 and NID 532, regionidentification level 540 comprises region entries 541-544, and accesspoint identification level 550 comprises access point entries 551-579(skipping even numbers, as seen in FIG. 6). NID entries 531 and 532 maycomprise one or more network identifiers that may identify one or morenetwork providers, for one example. Region entries 541-544 may compriseone or more region identification values or one or more regionidentifiers, and access point entries 551-579 may comprise one or moreaccess point identification values, in an aspect. Of course, the exampleorganization depicted for hierarchal wireless transmitter almanac 500 ismerely an example, and the scope of claimed subject matter is notlimited in these respects. For example, the scope of claimed subjectmatter is not limited to the specific numbers or types of levelsdepicted for hierarchal wireless transmitter almanac 500. Similarly, thescope of claimed subject matter is not limited to the depicted numbersor types of entries within the various levels of hierarchal wirelesstransmitter almanac 500.

In an additional aspect, some networks do not utilize hierarchicalencoding schemes. Wireless access points, such as those that may be partof WLAN 332, for example, may be organized in an ad hoc manner,according to where their owners place them. A wireless access pointalmanac is likely to be more dense, due to a larger number oftransmitters. The wireless transmitters to be included in a BSA subsetto be transmitted to a mobile station such as mobile station 322 may beselected based at least in part on their locations within ageometrically shaped area specified by the mobile station, or by theinclusion of their coverage areas in the specified area. The granularityof the information provided may be greater at the center of the area ofinterest than at locations farther away, in one aspect. This would allowmobile station 322 to receive BSA information from BSA server 350 withmore density and accuracy where mobile station 322 is likely to belocated in the near term, but also have almanac information for abroader area. For example, mobile station 322 may specify in its requestto BSA server 350 the densest almanac nearest its own estimatedlocation, and may also specify coarser almanac information at furtherdistances.

FIG. 6 is an illustration of a map 600 depicting example locations for anumber of wireless transceivers, labeled as black dots on map 600. Forthe example of FIG. 6, map 600 depicts access points 601, 603, 605, 607,609, 611, 613, 615, 617, 619, 621, 625, 627, and 629 distributed invarious locations. Access points 601-629 in an aspect may comprise WLANaccess points, although the scope of claimed subject matter is notlimited in this respect. Also depicted in map 600 are an airport 602, afreeway 620, a hospital 606, an office building complex 619, anautomobile service station 608, and an office building 604. Map 600further depicts a number of streets running north and south, labeled664, 666, 668, 672, and street 662 providing access to airport 602.Also, several streets are depicted running east and west, labeled 651,653, 655, 657, 659, and 661. Of course, map 600 and its variouscomponents are merely presented for purposes of facilitating discussionof various aspects of claimed subject matter. Map 600 and its componentsare not meant to depict a realistic or accurate arrangement orconfiguration of buildings, streets, or access points, for example.

As previously discussed, a mobile station such as mobile station 322 maybe provided a subset of almanac information based, at least in part, onexpected contributions from individual access points of a plurality ofaccess points to future navigation operations for mobile station 322.Expected contributions may be based, for example, on a value of theexpected contribution and also on a likelihood of having one or moresignals acquired by mobile station 322 for the individual access points.Further, in an aspect, likelihoods of having one or more signalsacquired by mobile station 322 for the individual access points may bebased, at least in part, on an individual access point's proximity to acurrent location of mobile station 322. For example, assume that mobilestation 322 estimates its location to be at position “A” on map 600,located at hospital 606 on street 664 between streets 657 and 659. In anaspect, mobile station 422 may have sufficient data storage capacity tohold almanac information for access points 601-629. However, in a morerealistic setting, a region such as that depicted in map 600 wouldlikely include a great deal more access points than those depicted. Forexample, each of office buildings 604 and 610 may have a number ofaccess points inside the building. Many homes, offices, retailestablishments, restaurants, etc., may incorporate access points inorder to provide Wi-Fi access to residents, tenants, customers,employees, travelers, and so forth. However, for purposes ofexplanation, it is assumed for the examples related to FIG. 6 thataccess points 601-629 represent all of the access points with known orestimated information available for storage in an almanac.

For the examples related to FIG. 6 and map 600, mobile station 322 mayhave access to hierarchal wireless transmitter almanac 500. For one ormore examples, the area depicted in map 600 may correspond to regionentry 541 of hierarchal wireless transmitter almanac 500, depicted inFIG. 5. Access points 601-629 are respectively associated with accesspoint entries 551-579 in access point identification level 550 ofhierarchal wireless transmitter almanac 500. Note that the access pointentries 551-579 of access point identification level 550 are associatedwith region entry 541. In an aspect, region entry 541 may includeinformation identifying access point entries 551-579 as being associatedwith region entry 541. Region entry 541 may comprise information that iscommon to all or most of the access points that relate back to regionentry 541. For example, if all of the access points are compatible withthe IEEE 801.11g standard, region entry 541 may store that information,and that information would not need to be stored in the individualaccess point entries 551-579.

Returning to the example where mobile station 322 is located at position“A” at hospital 606, a determination may be made by a network entitysuch as download manager 450 or BSA server 350 as to which of theplurality of access points 601-629 are likely to have one or moresignals acquired by mobile station 322 in the near term. For thisexample, a determination may be based, at least in part, on proximitiesof the individual access points to an estimated location of mobilestation 322. In an aspect, access points closest in range to position“A” would have a greater likelihood of having signals acquired by mobilestation 322 in the near term. In another aspect, a determination may bemade as to which of access points 601-629 are closest in range toposition “A”, and at least in part in response to such a determination,almanac information associated with those access points determined to beclosest in range to position “A” may be delivered to mobile station 322.In this manner, as mobile station 322 moves from point “A”, almanacinformation for those access points that mobile station 322 is likely toobserve is already stored at mobile station 322. For this example,access points 607, 609, and 627 may be determined to be likely to havesignals acquired by mobile station 322. Of course, in an actualimplementation, many more access points may be involved. In anotheraspect, position fixes for mobile station 322 may be repeatedperiodically, and almanac information stored at mobile station 322 maybe updated accordingly.

Another example technique mentioned above may relate to determining thelikelihoods of having one or more signals acquired by mobile station 322for individual access points of a plurality of access points based, atleast in part, on a number of occurrences over a period of time in whichmobile station 322 has acquired signals from individual access points inthe past. For the present example, assume that a user carries mobilestation 322 with him/her to work 5 times a week, and further assume thatthe user's path to get to work includes driving east to west on street653 past access points 621 and 625. The user returns from work drivingwest to east along the same street, again passing by access points 621and 625. Therefore, for this simple example, access points 621 and 625are observed by mobile station 322 at least 10 times per week.Additionally, assume that the user rarely travels along street 651.Therefore, mobile station 322 would rarely observe access point 615. Asa result, for this example, access points 621 and 625 may be determinedto have a likelihood of having one or more signals acquired by mobilestation 322, and mobile station 322 may be provided almanac informationrelated to those access points. Also, although for this example accesspoint 615 is relatively close in distance to access point 625, becausemobile station 322 rarely observes access point 615, almanac informationfor access point 615 may not be provided to mobile station 322, forexample.

For an additional example, a technique for determining likelihoods ofhaving one or more signals acquired by mobile station 322 for individualaccess points of a plurality of access points may include determiningsuch likelihoods based, at least in part, on an individual accesspoint's proximity to a historical route of mobile station 322. Returningto map 600, assume that the user occasionally caries mobile station 322with him/her while traveling along freeway 620, moving south-to-north.For this simple example, although it may not happen often, every oralmost every time mobile station observes access points 603, 605, and607, in that order, mobile station 322 continues on to observe accesspoints 609, 611, and 613. Therefore, a network resource such as downloadmanager 450 or BSA server 350 may, upon determining that mobile station322 is proceeding along a historical route with a likelihood that mobilestation will observe access points along that path, provide mobilestation 322 with almanac information related to the access points alongthat historical route.

As another example of a historical route, assume that a majority of thetime that mobile station 322 observes access points 605 then 601,indicating traveling to airport 602, mobile station next finds itself atSan Francisco International airport (SFO). For this example, if downloadmanager 450 determines that mobile station 322 has observed accesspoints 605 and 601 in succession, download manager may provide almanacinformation related to SFO to mobile station 322 so that should mobilestation 322 indeed end up at SFO, it will already have stored thereinthe desired almanac information, and navigation may commence immediatelyupon arrival.

In an additional aspect, a technique for determining likelihoods ofhaving one or more signals acquired by mobile station 322 for individualaccess points of a plurality of access points may include determiningsuch likelihoods based, at least in part, on an individual accesspoint's proximity to a predicted route of mobile station 322. In anaspect, a predicted route may be based, at least in part, on one or morehistorical routes of mobile station 322, although claimed subject matteris not limited in scope in this respect. In another aspect, as mentionedpreviously, likelihoods may be based, at least in part, on radio accesstypes supported by mobile station 322. Likelihoods may also be based, atleast in part, on rates of use for the individual radio access typessupported by mobile station 322, on radio access types currently enabledon mobile station 322, or may also be based, at least in part, on anumber of occurrences over a period of time in which an individualwireless transmitter has signals acquired by a plurality of other mobilestations reporting their observations to a network entity such asdownload manager 450. Of course, these are merely examples ofinformation that may be utilized in determining likelihoods of havingone or more signals acquired by a mobile station for individual wirelesstransmitters of a plurality of wireless transmitters, and the scope ofclaimed subject matter is not limited in this respect.

In examples described herein, a mobile station such as mobile station322 is described as requesting BSA information from BSA server 350. Inresponse to receiving the request from mobile station 322, BSA server350 configures the appropriate information and delivers the configuredinformation to mobile station 322. However, there may be a number ofvariations to these examples, in that there may be various techniques tocommunicate BSA information to mobile station 322. In some cases, thetechnique used may depend at least in part on a particular type of airinterface. In some air interfaces, a transmitting entity may also beable to store and forward its own BSA information or that of itsneighbors. For example, referring to FIG. 1, base station 132 may storeBSA information, and may forward at least a portion of that BSAinformation to mobile station 150 upon receiving a request from mobilestation 150. Base station 132 may compress or encrypt the information inaccordance with the examples mentioned above. In another aspect, basestation 132 may authenticate mobile station 150 before granting themobile station's request for BSA information.

Additionally, in one aspect, base station 132 may periodically broadcastBSA information to mobile stations that are within range and that havethe capability and authority to communicate with base station 132. Sucha transmission may be made with or without prompting from a mobilestation or from another network entity. In another aspect, mobilestation 150 may be provided a uniform resource locator (URL) that pointsto a network location from where mobile station 150 may obtain BSAinformation. For the example of FIG. 1, the network entity may compriseBSA server 180. However, as depicted in FIG. 3, a mobile station mayalso obtain database information from a third party external almanacsource 360, for another example. In an aspect, a mobile station such asmobile station 324 may subscribe to a service from the third partyexternal almanac source 360 that provides on-demand BSA updates.Alternatively, in another aspect, the third party external almanacsource 360 may provide the updates on a periodic basis, or whenever aneed arises due to system reconfiguration, for example.

As noted previously, BSA server 350 may receive BSA information from athird party in one aspect. In another aspect, BSA server 350 or anyother network entity that stores BSA information, such as one or morebase stations or access points, may receive BSA information gatheredfrom one or more mobile stations. The information gathered from themobile stations may comprise information gathered during positionestimation operations, for example. In another aspect, some mobilestations may store a database of transmitters from which they havereceived signals. The database may comprise, in one aspect, certainattributes about those transmitters, such as, for example, locationinformation, carrier frequency, etc. This information may have beenprovided to the mobile stations by the wireless network, or theinformation may have been derived by the mobile stations themselves.Regardless of the source, the gathered information may be desirable inthe development and maintenance of a BSA that may be used by mobilestations in a given area.

In an additional aspect, a mobile station may be expected to report aspecified amount of information to a base station almanac server, forexample, in exchange for more complete BSA information. Informationgathered and reported by the mobile station may comprise a series oflocations along with respective location uncertainties, and may furthercomprise discovered attributes of transmitters the mobile stationobserved from those locations. The attributes might include transmitteridentification information, for example, as well as signal carrierfrequency, relative or absolute signal strength, color coding, slottiming, or any other pertinent information that may help the BSA serverto map the coverage area of the individual transmitters. The attributesmay further include code phase for individual transmitters, or timingrelationships between some standard timing source (such as SPS time) andthe framing structure of one or more received signals.

FIG. 7 is a flow diagram of an example process for determining a subsetof wireless transmitter almanac information to transmit to a mobilestation, based at least in part on one or more expected contributions ofone or more respective wireless transmitters to a future navigationoperation for the mobile station. At block 710, an expected contributionto a future navigation operation for a mobile station may be determinedfor individual wireless transmitters of a plurality of wirelesstransmitters based at least in part on a value of the expectedcontribution and a likelihood of having one or more signals acquired bythe mobile station for the individual wireless transmitters of theplurality of wireless transmitters. In an aspect, values for expectedcontributions may be based, by way of non-limiting example, on rangingcapability, expected measurement or observation accuracy, coverage areasize, or statistics related to the importance of a particulartransmitter in previous navigation operations. Examples of possibletechniques for determining likelihoods of having one or more signalsacquired by a mobile station for the individual wireless transmittersare discussed above, and may include, for example, determining suchlikelihoods based, at least in part, on an individual transmitter'sproximity to a current location the mobile station, or, in anotheraspect, such likelihoods may be based, at least in part, on how oftenthe mobile station has acquired signals from an individual wirelesstransmitter in the past. For additional examples, likelihoods may bebased, at least in part, on an individual transmitter's proximity to ahistorical route of a mobile station, or, in another aspect, suchlikelihoods may be based, at least in part, on radio access typessupported by a mobile station. Likelihoods may also be based, at leastin part, on rates of use for the individual radio access types supportedby the mobile station, on radio access types currently enabled on themobile station, or may also be based, at least in part, on a number ofoccurrences over a period of time in which an individual wirelesstransmitter has signals acquired by a plurality of other mobile stationsreporting their observations to a network entity such as a downloadmanager or BSA server. Likelihoods may be based, at least in part, on anindividual transmitter's proximity to a predicted route of a mobilestation, or on whether a mobile station is authorized to communicatethrough the wireless transmitter, for other examples.

At block 720, a subset of wireless transmitters may be determined basedat least in part on the determined expected contributions for theindividual wireless transmitters. In an aspect, determining the subsetof wireless transmitters may comprise determining whether thelikelihoods for the individual wireless transmitters exceed apre-selected threshold. At block 730, almanac information for thedetermined subset of wireless transmitters may be identified. Examplesin accordance with claimed subject matter may include all of, less than,or more than blocks 710-730. Further, the order of blocks 710-730 ismerely an example order, and the scope of claimed subject matter is notlimited in this respect.

FIG. 8 is a block diagram of an example of mobile station 800 that maybe adapted to perform any of the example techniques described herein inconnection with FIGS. 1-7. One or more radio transceivers 870 may beadapted to modulate an RF carrier signal with baseband information, suchas voice or data, onto an RF carrier, and demodulate a modulated RFcarrier to obtain such baseband information. An antenna 872 may beadapted to transmit a modulated RF carrier over a wirelesscommunications link and receive a modulated RF carrier over a wirelesscommunications link.

A baseband processor 860 may be adapted to provide baseband informationfrom a central processing unit (CPU) 820 to transceiver 870 fortransmission over a wireless communications link. Here, CPU 820 mayobtain such baseband information from an input device within a userinterface 810. Baseband processor 860 may also be adapted to providebaseband information from transceiver 870 to CPU 820 for transmissionthrough an output device within user interface 810.

User interface 810 may comprise a plurality of devices for inputting oroutputting user information such as voice or data. Such devices mayinclude, by way of non-limiting examples, a keyboard, a display screen,a microphone, and a speaker.

A receiver 880 may be adapted to receive and demodulate transmissionsfrom an SPS, and provide demodulated information to correlator 840.Correlator 840 may be adapted to derive correlation functions from theinformation provided by receiver 880. Correlator 840 may also be adaptedto derive pilot-related correlation functions from information relatingto pilot signals provided by transceiver 870. This information may beused by a mobile station to acquire wireless communications services.Channel decoder 850 may be adapted to decode channel symbols receivedfrom baseband processor 860 into underlying source bits. In one examplewhere channel symbols comprise convolutionally encoded symbols, such achannel decoder may comprise a Viterbi decoder. In a second example,where channel symbols comprise serial or parallel concatenations ofconvolutional codes, channel decoder 850 may comprise a turbo decoder.

A memory 830 may be adapted to store machine-readable instructions whichare executable to perform one or more of processes, implementations, orexamples thereof which are described or suggested herein. CPU 820 may beadapted to access and execute such machine-readable instructions.

FIG. 9 is a schematic diagram illustrating an example system 900 thatmay include one or more devices configurable to implement techniques orprocesses described above, for example, in connection with exampletechniques for determining almanac information to provide to a mobilestation and for transmitting the almanac information, depicted in FIGS.1-7. System 900 may include, for example, a first device 902, a seconddevice 904, and a third device 906, which may be operatively coupledtogether through a wireless communications network 908.

First device 902, second device 904 and third device 906, as shown inFIG. 9, may be representative of any device, appliance or machine thatmay be configurable to exchange data over wireless communicationsnetwork 908. By way of example but not limitation, any of first device902, second device 904, or third device 906 may include: one or morecomputing devices or platforms, such as, e.g., a desktop computer, alaptop computer, a workstation, a server device, or the like; one ormore personal computing or communication devices or appliances, such as,e.g., a personal digital assistant, mobile communication device, or thelike; a computing system or associated service provider capability, suchas, e.g., a database or data storage service provider/system, a networkservice provider/system, an Internet or intranet serviceprovider/system, a portal or search engine service provider/system, awireless communication service provider/system; or any combinationthereof. Any of the first, second, and third devices 902, 904, and 906,respectively, may comprise one or more of a base station almanac server,a base station, or a mobile station in accordance with the examplesdescribed herein.

Similarly, wireless communications network 908, as shown in FIG. 5, isrepresentative of one or more communication links, processes, orresources configurable to support the exchange of data between at leasttwo of first device 902, second device 904, and third device 906. By wayof example but not limitation, wireless communications network 908 mayinclude wireless or wired communication links, telephone ortelecommunications systems, data buses or channels, optical fibers,terrestrial or space vehicle resources, local area networks, wide areanetworks, intranets, the Internet, routers or switches, and the like, orany combination thereof. As illustrated, for example, by the dashedlined box illustrated as being partially obscured of third device 906,there may be additional like devices operatively coupled to wirelesscommunications network 908.

It is recognized that all or part of the various devices and networksshown in system 900, and the processes and methods as further describedherein, may be implemented using or otherwise including hardware,firmware, software, or any combination thereof.

Thus, by way of example but not limitation, second device 904 mayinclude at least one processing unit 920 that is operatively coupled toa memory 922 through a bus 928.

Processing unit 920 is representative of one or more circuitsconfigurable to perform at least a portion of a data computing procedureor process. By way of example but not limitation, processing unit 920may include one or more processors, controllers, microprocessors,microcontrollers, application specific integrated circuits, digitalsignal processors, programmable logic devices, field programmable gatearrays, and the like, or any combination thereof.

Memory 922 is representative of any data storage mechanism. Memory 922may include, for example, a primary memory 924 or a secondary memory926. Primary memory 924 may include, for example, a random accessmemory, read only memory, etc. While illustrated in this example asbeing separate from processing unit 920, it should be understood thatall or part of primary memory 924 may be provided within or otherwiseco-located/coupled with processing unit 920.

Secondary memory 926 may include, for example, the same or similar typeof memory as primary memory or one or more data storage devices orsystems, such as, for example, a disk drive, an optical disc drive, atape drive, a solid state memory drive, etc. In certain implementations,secondary memory 926 may be operatively receptive of, or otherwiseconfigurable to couple to, a computer-readable medium 940.Computer-readable medium 940 may include, for example, any medium thatcan carry or make accessible data, code or instructions for one or moreof the devices in system 900. Computer readable medium 940 may also bereferred to as a storage medium.

Second device 904 may include, for example, a communication interface930 that provides for or otherwise supports the operative coupling ofsecond device 904 to at least wireless communications network 908. Byway of example but not limitation, communication interface 930 mayinclude a network interface device or card, a modem, a router, a switch,a transceiver, and the like.

Second device 904 may include, for example, an input/output device 932.Input/output device 932 is representative of one or more devices orfeatures that may be configurable to accept or otherwise introduce humanor machine inputs, or one or more devices or features that may beconfigurable to deliver or otherwise provide for human or machineoutputs. By way of example but not limitation, input/output device 932may include an operatively configured display, speaker, keyboard, mouse,trackball, touch screen, data port, etc.

The methodologies described herein may be implemented by various meansdepending upon applications according to particular examples. Forexample, such methodologies may be implemented in hardware, firmware,software, or combinations thereof. In a hardware implementation, forexample, a processing unit may be implemented within one or moreapplication specific integrated circuits (ASICs), digital signalprocessors (DSPs), digital signal processing devices (DSPDs),programmable logic devices (PLDs), field programmable gate arrays(FPGAs), processors, controllers, microcontrollers, microprocessors,electronic devices, other devices units designed to perform thefunctions described herein, or combinations thereof.

“Instructions” as referred to herein relate to expressions whichrepresent one or more logical operations. For example, instructions maybe “machine-readable” by being interpretable by a machine for executingone or more operations on one or more data objects. However, this ismerely an example of instructions and claimed subject matter is notlimited in this respect. In another example, instructions as referred toherein may relate to encoded commands which are executable by aprocessing circuit having a command set which includes the encodedcommands. Such an instruction may be encoded in the form of a machinelanguage understood by the processing circuit. Again, these are merelyexamples of an instruction and claimed subject matter is not limited inthis respect.

“Storage medium” as referred to herein relates to media capable ofmaintaining expressions which are perceivable by one or more machines.For example, a storage medium may comprise one or more storage devicesfor storing machine-readable instructions or information. Such storagedevices may comprise any one of several media types including, forexample, magnetic, optical or semiconductor storage media. Such storagedevices may also comprise any type of long term, short term, volatile ornon-volatile memory devices. However, these are merely examples of astorage medium, and claimed subject matter is not limited in theserespects.

Some portions of the detailed description included herein are presentedin terms of algorithms or symbolic representations of operations onbinary digital signals stored within a memory of a specific apparatus orspecial purpose computing device or platform. In the context of thisparticular specification, the term specific apparatus or the likeincludes a general purpose computer once it is programmed to performparticular operations pursuant to instructions from program software.Algorithmic descriptions or symbolic representations are examples oftechniques used by those of ordinary skill in the signal processing orrelated arts to convey the substance of their work to others skilled inthe art. An algorithm is here, and generally, is considered to be aself-consistent sequence of operations or similar signal processingleading to a desired result. In this context, operations or processinginvolve physical manipulation of physical quantities. Typically,although not necessarily, such quantities may take the form ofelectrical or magnetic signals capable of being stored, transferred,combined, compared or otherwise manipulated. It has proven convenient attimes, principally for reasons of common usage, to refer to such signalsas bits, data, values, elements, symbols, characters, terms, numbers,numerals, or the like. It should be understood, however, that all ofthese or similar terms are to be associated with appropriate physicalquantities and are merely convenient labels. Unless specifically statedotherwise, as apparent from the discussion herein, it is appreciatedthat throughout this specification discussions utilizing terms such as“processing,” “computing,” “calculating,” “determining” or the likerefer to actions or processes of a specific apparatus, such as a specialpurpose computer or a similar special purpose electronic computingdevice. In the context of this specification, therefore, a specialpurpose computer or a similar special purpose electronic computingdevice is capable of manipulating or transforming signals, typicallyrepresented as physical electronic or magnetic quantities withinmemories, registers, or other information storage devices, transmissiondevices, or display devices of the special purpose computer or similarspecial purpose electronic computing device.

Wireless communication techniques described herein may be in connectionwith various wireless communications networks such as a wireless widearea network (WWAN), a wireless local area network (WLAN), a wirelesspersonal area network (WPAN), and so on. The term “network” and “system”may be used interchangeably herein. A WWAN may be a Code DivisionMultiple Access (CDMA) network, a Time Division Multiple Access (TDMA)network, a Frequency Division Multiple Access (FDMA) network, anOrthogonal Frequency Division Multiple Access (OFDMA) network, aSingle-Carrier Frequency Division Multiple Access (SC-FDMA) network, orany combination of the above networks, and so on. A CDMA network mayimplement one or more radio access technologies (RATs) such as cdma2000,Wideband-CDMA (W-CDMA), to name just a few radio technologies. Here,cdma2000 may include technologies implemented according to IS-95,IS-2000, and IS-856 standards. A TDMA network may implement GlobalSystem for Mobile Communications (GSM), Digital Advanced Mobile PhoneSystem (D-AMPS), or some other RAT. GSM and W-CDMA are described indocuments from a consortium named “3rd Generation Partnership Project”(3GPP). Cdma2000 is described in documents from a consortium named “3rdGeneration Partnership Project 2” (3GPP2). 3GPP and 3GPP2 documents arepublicly available. A WLAN may comprise an IEEE 802.11x network, and aWPAN may comprise a Bluetooth network, an IEEE 802.15x, for example.Wireless communication implementations described herein may also be usedin connection with any combination of WWAN, WLAN or WPAN.

The terms, “and,” and “or” as used herein may include a variety ofmeanings that will depend at least in part upon the context in which itis used. Typically, “or” if used to associate a list, such as A, B or C,is intended to mean A, B, and C, here used in the inclusive sense, aswell as A, B or C, here used in the exclusive sense. Referencethroughout this specification to “one example” or “an example” meansthat a particular feature, structure, or characteristic described inconnection with the example is included in at least one example ofclaimed subject matter. Thus, the appearances of the phrase “in oneexample” or “an example” in various places throughout this specificationare not necessarily all referring to the same example. Furthermore, theparticular features, structures, or characteristics may be combined inone or more examples. Examples described herein may include machines,devices, engines, or apparatuses that operate using digital signals.Such signals may comprise electronic signals, optical signals,electromagnetic signals, or any form of energy that provides informationbetween locations.

While there has been illustrated and described what are presentlyconsidered to be example features, it will be understood by thoseskilled in the art that various other modifications may be made, andequivalents may be substituted, without departing from claimed subjectmatter. Additionally, many modifications may be made to adapt aparticular situation to the teachings of claimed subject matter withoutdeparting from the central concept described herein. Therefore, it isintended that claimed subject matter not be limited to the particularexamples disclosed, but that such claimed subject matter may alsoinclude all aspects falling within the scope of the appended claims, andequivalents thereof.

What is claimed is:
 1. A method for estimating positions of a mobilestation, the method comprising: sending a request, from the mobilestation, for almanac information for wireless transmitters of one ormore wireless communications networks, the request including one or moreindications of one or more routes; receiving, at the mobile station, thealmanac information for wireless transmitters of the one or morewireless communications networks, the almanac information being for asubset of wireless transmitters of the wireless transmitters of the oneor more wireless communications networks, the subset of wirelesstransmitters being expected to contribute to position estimations of themobile station along the one or more routes; acquiring signals, at themobile station, from a plurality of wireless transmitters of the subsetof wireless transmitters; and estimating, at the mobile station, aplurality of positions of the mobile station using at least one of theacquired signals from the plurality of wireless transmitters.
 2. Themethod of claim 1, wherein the request specifies a maximum amount of thealmanac information.
 3. The method of claim 1, wherein the requestspecifies a wireless transmitter coverage area or a wireless transmittertype.
 4. The method of claim 1, wherein the request specifies aparticular wireless communications network.
 5. The method of claim 1,wherein the request includes a request for more dense almanacinformation near an estimated location of the mobile station.
 6. Themethod of claim 1, wherein the one or more routes comprises a predictedroute.
 7. The method of claim 1, wherein the one or more routescomprises a historical route.
 8. The method of claim 1, furthercomprising sending, from the mobile station, one or more signalsindicative of almanac information for the plurality of wirelesstransmitters of the subset of wireless transmitters.
 9. A mobile stationcomprising: a transceiver; a processor communicatively coupled to thetransceiver and configured to: send, via the transceiver, a request foralmanac information for wireless transmitters of one or more wirelesscommunications networks, the request including one or more indicationsof one or more routes; receive, via the transceiver, the almanacinformation for wireless transmitters of the one or more wirelesscommunications networks, the almanac information being for a subset ofwireless transmitters of the wireless transmitters of the one or morewireless communications networks, the subset of wireless transmittersbeing expected to contribute to position estimations of the mobilestation along the one or more routes; acquire signals, via thetransceiver, from a plurality of wireless transmitters of the subset ofwireless transmitters; and estimate a plurality of positions of themobile station using at least one of the acquired signals from theplurality of wireless transmitters.
 10. The mobile station of claim 9,wherein the processor is configured to produce the request specifying amaximum amount of the almanac information.
 11. The mobile station ofclaim 9, wherein the processor is configured to produce the requestspecifying a wireless transmitter coverage area or a wirelesstransmitter type.
 12. The mobile station of claim 9, wherein theprocessor is configured to produce the request specifying a particularwireless communications network.
 13. The mobile station of claim 9,wherein the processor is configured to produce the request including arequest for more dense almanac information near an estimated location ofthe mobile station.
 14. The mobile station of claim 9, wherein theprocessor is configured to produce the request specifying a predictedroute among the one or more routes.
 15. The mobile station of claim 9,wherein the processor is configured to produce the request specifying ahistorical route among the one or more routes.
 16. The mobile station ofclaim 9, wherein the processor is further configured to send, via thetransceiver, one or more signals indicative of almanac information forthe plurality of wireless transmitters of the subset of wirelesstransmitters.
 17. A non-transitory computer-readable medium includingprogram code stored thereon configured to cause a computer, on a mobilestation, to: send a request for almanac information for wirelesstransmitters of one or more wireless communications networks, therequest including one or more indications of one or more routes; receivethe almanac information for wireless transmitters of the one or morewireless communications networks, the almanac information being for asubset of wireless transmitters of the wireless transmitters of the oneor more wireless communications networks, the subset of wirelesstransmitters being expected to contribute to position estimations of themobile station along the one or more routes; acquire signals from aplurality of wireless transmitters of the subset of wirelesstransmitters; and estimate a plurality of positions of the mobilestation using at least one of the acquired signals from the plurality ofwireless transmitters.
 18. The computer-readable medium of claim 17,further comprising code configured to cause the computer to produce therequest specifying a maximum amount of the almanac information.
 19. Thecomputer-readable medium of claim 17, further comprising code configuredto cause the computer to produce the request specifying a wirelesstransmitter coverage area or a wireless transmitter type.
 20. Thecomputer-readable medium of claim 17, further comprising code configuredto cause the computer to produce the request specifying a particularwireless communications network.
 21. The computer-readable medium ofclaim 17, further comprising code configured to cause the computer toproduce the request including a request for more dense almanacinformation near an estimated location of the mobile station.
 22. Thecomputer-readable medium of claim 17, further comprising code configuredto cause the computer to produce the request specifying a predictedroute among the one or more routes.
 23. The computer-readable medium ofclaim 17, further comprising code configured to cause the computer toproduce the request specifying a historical route among the one or moreroutes.
 24. The computer-readable medium of claim 17, further comprisingcode configured to cause the computer to send one or more signalsindicative of almanac information for the plurality of wirelesstransmitters of the subset of wireless transmitters.